The Dynamic Changes Of Neurotrophin-4/5 Expression In Brain In Experimental Streptococcus Pneumoniae Meningitis

Objective:To investigate the expression of neurotrophin-4/5 (NT -4/5) protein in infancy rats and to investigate the relationship between the expression of NT-4/5 and antibiotic was administed after exposure to experimental Streptococcus pneumoniae meningitis; To investigate the relationship between dexamethasone was administed and expression of neurotrophin-4/5 in experimental Streptococcus pneumoniae meningitis.Methods:1.Three weeks old rats were used to construct the models of Streptococcus pneumoniae meningitis and normal . At 24 h , 48h,5d after inoculating, the expression of NT-4/5 protein were detected by immunohistochemical staining methods in cerebral cortex and hippocampus. 2. To construct the models of Streptococcus pneumoniae meningitis and normal in 3 weeks old rats , then they were administed by antibiotic respectively. Neurotrophin -4/5 protein in cerebral cortex and hippocampus were detected by immunohistochemical staining methods, respectively. 3. To construct the models of Streptococcus pneumoniae meningitis in 3 weeks old rats and normal , then they were administed by antibiotic plus dexamethasone respectively, neurotrophin-4/5 protein in cerebral cortex and hippocampus were detected by immunohistochemical staining methods, respectively.Results :In cerebral cortex and hippocampus, the expression of NT-4/5 protein is up-regulated obviously at 24 h after infection compared to controls( P < 0.05 ), but the expression of NT -4/5 protein at 48h is identical compare to the group after infection 24h(P> 0. 05 ). The expression of NT-4/5 protein is delined at 5d compared to 24h,but it can not arrive to the level of controls at 5d in this experiment(P < 0.05 ). The expression of neurotrophin-4/5 protein of the group after administration by antibiotics after infection 5 days is up-regulated than the 5 days control levels after administration by antibiotics (P < 0.05), and it is lower compare to the group after infection 5 days (P> 0. 05) ; In control, The expression of neurotrophin -4/5 protein after administration by antibiotics , there was no change compared to 5 days control levels (P> 0. 05 ). After administration by antibiotics plus DEX, the expression of neurotrophin-4/5 protein compare to administration by antibiotics was greater after infection 24 h( P < 0. 05 ), and is greater than controls after administration by antibiotics plus DEX ( P < 0.05 ); In control, after administration by antibiotics plus DEX , the expression of neurotrophin -4/5 protein was greater than after administration by antibiotics that in cerebral cortex and hippocampus (P < 0. 05 ). In control, The expression of neurotrophin -4/5 protein at 24h is no change compared to 5 days control levels (P> 0. 05 ).There are no positive staining consequence in negative control.Conclusions :These results support the hypothesis: 1. The up-regulation of NT -4/5 during Streptococcus Pneumoniae Meningitis maybe the self-protection of organism and this protection is obvious during earlier stage. 2. During Streptococcus Pneumoniae Meningitis,dexamethasone adjunctive therapy can up-regulate the expression of NT-4/5 in cerebral cortex and hippocampus,maybe profit for the enhancement of NT-4/5 to neurogenesis and the protection to the injury of the brain of Streptococcus Pneumoniae Meningitis. 3. Dexamethasone adjunctive therapy can up-regulate the expression of NT-4/5 in cerebral cortex and hippocampus in normal condition.